Variation in the perception of environmental health risks and adverse response to airborne chemical exposures constitutes a complex public health challenge for policy makers, the medical profession and the public. The goal of this project is to develop a comprehensive map of factors that determine how the subjective experience from an airborne chemical exposure is related to (1) the sensory and physiological effects that are directly elicited by the chemical and (2) the psychological processes involved in perception, memory and judgment that can indirectly mediate health effects from chemical exposures. Our findings to date continue to support the perspective that among healthy individuals, expectancies related to the chemical or the exposure situation, modulated by factors such as exposure history or personality type, lead to significant variation in an individual's response to a chemical exposure. These factors are likely to be enhanced and consequently have a greater public health impact for individuals with pre-existing respiratory disease, such as asthma. The current proposal will extend our understanding of the interaction between cognitive beliefs, expectancies and physiological responses to odors and irritants by studying those of asthmatics, for whom there is both greater perceived and actual health risk from chemical exposures. This effort will lead to better identification of the respiratory health impact of exposure to a range of odorous chemicals for nearly 17 million Americans, and may possibly identify therapies via autonomic regulation and feedback that may be particularly useful for ameliorating the adverse response of these individuals to a range of airborne chemical exposures.